Optial Dynamics of
Illusion

Op techniques permit the artist to go beyond the dynamic possibilities made available by compositional and graphic means--doing this by causing the eye to work overtime and to transmit its own activity to the page.

For example [the following compositional factors]:
Knowing that our eyes have a strong tendency to follow the run of a line--and also to string points mentally together to form a line--we might be given a multitude of lines to follow.

Knowing also that the longer and more unbroken the line, the more hypnotically the eye will follow it, one might ensure that the lines possess this quality in order to help us become optically mesmerized.

In addition, when the linear flow is strictly vertical and horizontal, we basically have only to cope with two dimensions of movement; but when a diagonal direction is taken, the sensation we receive is of the line cutting in or pushing out. This [diagonal direction] intensifies the sense of energetic movement in space, producing the seemingly concave troughs and convex ridges.

Another compositional factor adds to this optical alchemy--that of fitting the marks of drawing tightly together in a kind of ^close parallelism. The result of this technique is to further render the figure-ground situation ambiguous. What is figure and what is ground? Because of the uniformity of black lines and white spaces, for example, we might not tell which is which. Because we cannot cleanly separate figure from ground the eye--doing its best to visually clarify the situation--finds itself dazzled by the complexity of surface movement; by the shimmering effect seemingly given off by the image. In fact the movement or pulse we perceive in the drawing represents the movement of the eye itself as it focuses and refocuses, trying to clarify things and present a clean-cut figure-ground situation. [pgs. 207-209]